A spring of this type is known from the French Patent No. 1,090,004, which discloses a spring constituted by a rod of an elastic material axially provided with a longitudinal hole merging at at least one of the ends and in which incisions are provided forming transverse gaps which merge into the longitudinal hole with these gaps being shifted with respect to each other in the longitudinal and peripheral direction in such a manner that at least a series of elastic blades is left between them, which are interconnected zigzagwise.
Such a spring has to be thermally treated before being machined in order to avoid deformation due to the treatment and to obtain very accurate dimensions and the possibility of machining the ends, all this with good characteristics with respect to the quality of the elastic material. This spring can be made of steel, of bronze, of superpolyamide or of caoutchouc or rubber, with a milling operation being carried out on these materials.
Now the temperatures at which such springs can operate are just below 500.degree. C. and the latter cannot in any case fulfil the function of a spring operating at high temperatures, for example, at temperatures exceeding 1000.degree. C.
On the other hand, the applications which require the use of springs operating at high temperatures lie, for example, in the field of semiconductor metallurgy. Now in such an application, the problem of pollution of the environment in which the springs operate is of major importance and the materials described in French Patent No. 1,090,004 are not adapted to this use. A change of materials is imposed and a choice has to be made among refractory materials, such as quartz, boron nitride and graphite. However, the milling operation used according to this document does not permit obtaining an elastic element that can fulfil the function of a spring. In fact, these milling operations generate microcracks mainly in the zones in which the elasticity of the material is applied, while fractures appear in the elements obtained, which render the elements thus formed unsuitable for any function of a spring operating at high temperature.